509
FXUS63 KARX 240840
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
340 AM CDT THU APR 24 2025
KEY MESSAGES
- PERIODIC SHOWERS AND THUNDERSTORMS CONTINUE TODAY AND TONIGHT.
ORGANIZED SEVERE STORMS ARE NOT EXPECTED, HOWEVER COULD SEE A
FEW THAT ARE STRONG TO SEVERE STORM WITH HAIL.
- ADDITIONAL RAINFALL OF 0.25 TO 1.25" THROUGH FRIDAY MORNING.
SOME RIVERS ARE CURRENTLY ELEVATED/FLOODING (THE BLACK RIVER
AND THE YELLOW RIVER). MORE LOCALIZED FLOODING POSSIBLE
TONIGHT ESPECIALLY SHOULD HIGHER 1.5" TO 2.5" AMOUNTS FALL.
- A STRONG TROUGH COULD BRING THE RISK OF ORGANIZED SEVERE
WEATHER AND MORE RAINFALL TO THE REGION NEXT MONDAY AND
TUESDAY, ALONG WITH SEASONABLY WARM TEMPERATURES IN THE 70S.
DISCUSSION
ISSUED AT 328 AM CDT THU APR 24 2025
OVERVIEW:
LATEST WATER VAPOR SATELLITE IMAGERY, HEIGHTS AND LIGHTNING SHOWED
THAT THE MORE ZONAL FLOW WAS OVER THE GREAT LAKES AND OHIO RIVER
VALLEY WITH A 500MB TROUGH OVER IDAHO/NEVADA AND HEIGHTS LOWERING IN-
BETWEEN WITH SOUTHWEST FLOW AND EMBEDDED RIPPLES IN THE FLOW.
SEVERAL CLUSTERS OF STORMS WERE OVER THE CENTRAL U.S. FROM TEXAS
THROUGH THE PLAINS. ANOTHER CLUSTER OF STORMS WAS PUSHING ACROSS
NORTHEAST IOWA INTO SOUTHERN WISCONSIN. THE 24.00 MPX SOUNDING
SHOWED STEEP LAPSE RATES WITH AROUND 0.50" OF PWAT. THE KDVN
SOUNDINGS ALSO HAD STEEP LAPSE RATES WITH PWATS AROUND 0.8". THE
SURFACE FRONT HAS PUSHED TO THE SOUTH OF THE FORECAST AREA, HOWEVER
SURFACE DEWPOINTS STILL LINGER IN THE 50S TOWARD DBQ. AT 08Z THE
LATEST WSR-88D REFLECTIVITY CONTINUED TO SHOW SHOWERS OVER PARTS OF
NORTHEAST IOWA INTO SOUTHERN WISCONSIN WITH ADDITIONAL SHOWERS
IN SOUTHEAST MINNESOTA INTO WEST CENTRAL WISCONSIN.
THROUGH FRIDAY
AN 85 TO 95KT UPPER LEVEL JET CONTINUES ACROSS THE NORTHERN U.S. AND
WILL CONTINUE TO LIFT NORTHEAST ACROSS SOUTHERN CANADA. TODAY AND
TONIGHT, THERE CONTINUES TO BE UPPER LEVEL SUPPORT ENHANCING
PRECIPITATION. THE SOUTHWEST FLOW ALOFT CONTINUES AS AN 500MB
WAVE OVER SASKATCHEWAN AND EMBEDDED RIPPLES OVER THE PLAINS AND
FOUR CORNERS REGION MOVE THROUGH THE REGION. THE SURFACE FRONT
MEANDERS ACROSS IOWA, SOUTHERN WISCONSIN AND INTO ILLINOIS, BUT
IS PUSHED SOUTH WITH DRYING BEHIND IT FRIDAY. SOME MOISTURE
TRANSPORT CONTINUES THIS MORNING WITH MLCAPE OF 100 TO 400 J/KG.
IN ADDITION, THE MOISTURE AXIS IS DRAPED FROM NORTHEAST IOWA
INTO SOUTHWEST WI WITH AROUND 1.1" PWAT IN THIS SAME LOCATION.
STEEP LAPSE RATES ARE IN PLACE AND SOME MID-LEVEL FRONTOGENESIS
IS PRESENT NEAR OR NORTH OF I94 THIS MORNING. THE MOISTURE
TRANSPORT INCREASES THIS AFTERNOON AND TONIGHT WITH LIMITED
INSTABILITY AND PWAT VALUES INCREASING ACROSS THE FORECAST AREA
TO 1.1" TO 1.25". THERE IS BROAD SCALE SYNOPTIC LIFT AND WARM
AIR ADVECTION/ISENTROPIC LIFT.
IT IS A MESSY PATTERN WITH PERIODS OF SHOWERS AND
THUNDERSTORMS. THERE IS NOT A UNIFORM LOW LEVEL JET THAT FOCUS
OVER THE AREA THUS MAKING THE TIMING AND LOCATION DIFFICULT TO
PIN DOWN. THERE WILL BE AREAS OF SHOWERS AND A FEW STORMS THIS
MORNING WITH A GENERAL INCREASE LATER THIS AFTERNOON AND TONIGHT
AS SHORTWAVE TROUGH ENERGY APPROACHES AND CONTINUES OVERNIGHT
WITH WIDESPREAD PRECIPITATION WITH THE TROUGH. THE SHOWERS AND
THUNDERSTORMS GENERALLY EXIT THE AREA FRIDAY MORNING. SOME
LAGGING TROUGH ENERGY COULD PRODUCE SOME SHOWERS CHANCES OVER
WISCONSIN, HOWEVER THE MOISTURE HAS PUSHED INTO EASTERN
WISCONSIN BY THEN. WE CURRENTLY ARE IN THE GENERAL THUNDER AREA.
OVERNIGHT, SOME STORMS HAVE PRODUCE SMALL HAIL. THERE IS A
STRONG 850MB GRADIENT THAT SETS UP JUST NORTH OF THE FORECAST
AREA AND WITH THE SURFACE BOUNDARY LIFTING BACK INTO NORTHEAST
IOWA AND SOUTHERN WISCONSIN WITH THE POTENTIAL FOR WARMER
TEMPERATURES, THESE WOULD BE TWO AREAS TO MONITOR FOR STRONGER
STORMS. DUE TO THE LOW FREEZING LEVELS AND SOME INSTABILITY
CANNOT RULE OUT SMALL HAIL TO ISOLATED SEVERE HAIL WITH STRONGER
STORMS.
HIGHS TODAY WILL RANGE FROM THE 50S TO THE 70S WITH THE 50S IN THE
NORTHERN PARTS OF THE FORECAST AREA. COOLER FOR FRIDAY WITH HIGHS
IN THE 50S AREA-WIDE. NORTH WINDS INCREASE 15 TO 30 MPH.
SEE HYDRO SECTION BELOW FOR PRECIPITATION DETAILS.
THE WEEKEND:
THE WEEKEND STILL LOOKS DRY FOR SATURDAY WITH PRECIPITATION CHANCES
RETURNING SUNDAY. ALTHOUGH A RIDGE BUILDS IN OVER THE AREA, RETURN
FLOW SET UPS AND MOISTURE TRANSPORT INCREASES. THE SHOWERS/STORMS
DEVELOP WITH THE MOISTURE RETURN. WILL WANT TO MONITOR ANY
STORMS DUE TO THE STRENGTHENING LOW LEVEL JET. INSTABILITY IS
LIMITED, HOWEVER SHEAR PROFILES INCREASE.
HIGH SATURDAY/SUNDAY RETURN TO SEASONAL LEVELS IN THE 60S EACH DAY.
SEVERE STORMS POTENTIAL MONDAY INTO TUESDAY:
WE CONTINUE TO MONITOR THE POTENTIAL FOR SEVERE STORMS MONDAY INTO
TUESDAY. 12Z MONDAY, AN AREA OF LOW PRESSURE IS FORECAST OVER SOUTH
DAKOTA WITH A WARM FRONT OVER WESTERN IOWA AND A COLD FRONT
THROUGH NEBRASKA/KANSAS. AS THE LONGWAVE TROUGH MOVES INTO THE
REGION, THE WARM FRONT LIFTS NORTH ACROSS THE FORECAST AREA AND
THE COLD FRONT MOVES THROUGH OVERNIGHT. THE VARIOUS
SPC/CSU/CIPS/AI OUTLOOKS FOR SEVERE WEATHER CONTINUE TO
HIGHLIGHT A POTENTIAL SEVERE WEATHER EVENT MONDAY FOR A LARGE
PART OF THE MISSOURI RIVER VALLEY INTO THE UPPER MISSISSIPPI
RIVER VALLEY; INCLUDING THE LOCAL FORECAST AREA. ALL MODES OF
SEVERE WEATHER WILL BE POSSIBLE. THE MAIN AXIS OF HEAVY RAIN IS
CURRENTLY EXPECTED TO BE NORTH OF THE LOCAL AREA, HOWEVER THERE
ARE SOME ECE/GEPS/GEFS 30 TO 50% PROBABILITIES OF .50"+ AMOUNTS
OF RAIN.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1052 PM CDT WED APR 23 2025
VFR CONDITIONS CURRENTLY PRESENT AT THE TERMINALS. SHOWERS AND
STORMS HAVE REMAINED ACROSS NORTHEASTERN IOWA AND FAR
SOUTHWESTERN WISCONSIN SO FAR THIS EVENING BUT ACTIVITY IS
EXPECTED TO SPREAD NORTH AND EAST INTO THE OVERNIGHT HOURS. HAVE
ADDED TEMPO GROUPINGS AT BOTH TERMINALS WITH INCREASED CONFIDENCE
IN COVERAGE FOR SHOWERS/STORMS AFTER 08Z. AFTERWARDS, WE'LL SEE
A LULL IN ACTIVITY UNTIL LATER IN THE AFTERNOON WITH ACTIVITY
FILLING IN FROM THE WEST. HAVE ADJUSTED PREVAILING AND PROB30
GROUPS TO ALIGN WITH THE LATEST HI-RESOLUTION GUIDANCE. ACTIVITY
WILL REALLY PICK UP AFTER 21Z THURSDAY WITH MVFR AND IFR
CEILINGS AND VISIBILITIES BUILDING INTO THE AREA - IMPACTING RST
FIRST AROUND 22Z AND LSE LATER AROUND 04Z FRIDAY. CEILINGS MAY
DROP TO LIFR FOR RST AROUND 06Z BUT DID NOT HAVE ENOUGH
CONFIDENCE TO INCLUDE WITH THIS PACKAGE. WILL HAVE TO MONITOR
THIS POSSIBILITY FOR FUTURE PACKAGE UPDATES.
HYDROLOGY
ISSUED AT 328 AM CDT THU APR 24 2025
ADDITIONAL RAIN OF .25 TO 1.25" THROUGH FRIDAY MORNING. SOME RIVERS
ARE CURRENTLY ELEVATED/FLOODING (THE BLACK RIVER AND THE YELLOW
RIVER). THE HREF ENSEMBLE MAX PRECIPITATION IS 1.5 TO 2.5" FROM
SOUTHEAST MINNESOTA INTO WESTERN WISCONSIN. THE LATEST 6-HR FLASH
FLOOD IS AROUND 2.25 INCHES. WITH THE STORMS THROUGH EARLY THIS
MORNING, AMOUNTS WERE MOSTLY TRACE TO .5", HOWEVER SOME
EMBEDDED .5 TO 1.5" MRMS RADAR ESTIMATES OCCURRED ON A LOCAL
BASIS. THUS, MOST AREAS SHOULD BE OK WITH THE AMOUNTS CURRENTLY
FORECAST, HOWEVER SOME FLOODING CAN BE EXPECTED ON A LOCAL BASIS
WHERE THE HIGHER AMOUNTS OCCUR AND WHERE RIVERS ARE ALREADY
ELEVATED.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...ZAPOTOCNY
AVIATION...BARENDSE
HYDROLOGY...ZAPOTOCNY
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